Colombine serves as one of the four master automatons, Les Quatre Pionniers, within the Midnight Circus, fulfilling the role of acrobat and rope walker. Her initial form features a green and black checkered vest with coat-tails, long yellow puffy sleeves adorned with orange stars and white fringe, and silver tights. A green mask obscures her upper face, with loose bandages wrapping her head, allowing her hair to peek through.

She desires romantic experiences like those in stories but faces a fundamental limitation: her mechanical body cannot perceive tactile sensations such as human touch. Her primary combat ability in this original body, "Melting Touch," generates intense heat in her hands capable of burning or melting objects. She also manipulates Zonapha insects present in the air, materializing them into weapons like spikes, platforms, or drills. Her signature weapons are named "Les Mains Blanches Immaculées".

Following severe damage sustained during a significant confrontation against the Midnight Circus in the Sahara Desert, Faceless of the Shirogane forces reconstructed her. This process resulted in a radically altered appearance: a much younger, pre-adolescent body resembling a small girl with blond hair, wide eyes, and dressed in a black Gothic Lolita-style outfit. This transformation permanently eliminated her "Melting Touch" ability, though her Zonapha manipulation remained intact.

Originally aligned with the Midnight Circus's goal of spreading Zonapha Syndrome to force laughter from their creator's companion, the Doll Francine, Colombine and the other Pioneers experienced a profound shift. Their destruction in the Sahara conflict and subsequent rebuilding by Faceless led to humiliation within the new Automaton hierarchy, rendering them obsolete and marginalized. This degradation, coupled with their lingering core directive to obey Francine, created an opening for change. When Éléonore (Shirogane), recognized as a legitimate heir to Francine's legacy, issued commands, Colombine and the other Pioneers underwent a Heel–Face Turn, abandoning the Midnight Circus to ally with humanity.

Operating under Éléonore's authority in this new allegiance, Colombine participated in the final conflicts against the forces threatening global stability. Ultimately, alongside Arlecchino and Pantalone, she achieved a measure of peace, fulfilling the core purpose embedded in her existence before meeting her end.